1. Field of the Invention
This invention relates to compositions containing an active or functional organic compound which requires solubilization, and more particularly, to such compositions which are effectively solubilized by addition of an aryl phenylethyl ester as solvent, cosolvent or additive.
2. Description of the Prior Art
Many commercial products, e.g. personal care, e.g. sunscreens, pharmaceutical, agricultural and industrial compositions, contain active or functional materials which require solubilization in the form of a solution, emulsion or dispersion, in aqueous or non-aqueous form. For example, a sunscreen formulation containing aromatic compounds such as avobenzone (Escalol® 517) and/or benzophenone-3 (Escalol® 567) as active UVA/UVB absorbing ingredients, requires a solubilization agent to keep it in an emulsion, i.e. to prevent crystallization. Several such solubilizers are known, e.g. ethyl benzoate or a C12-C15 alkyl benzoate; however, the former compound is a strong irritant, and the latter is only a poor solvent for avobenzone.
Previous syntheses of 2-phenylethyl benzoate have employed toxic solvents and/or expensive or toxic stoichiometric reagents. For example, 2-phenylethyl alcohol and benzoic acid have been condensed in acetonitrile solvent with the aid of a stoichiometric N,N,N′,N′-tetramethylchloroformamidinium chloride reagent, prepared in situ from N,N,N′,N′-tetramethylurea, oxalyl chloride and pyridine (Fujisawa et al., Chem. Lett. 1982, 1891-1894). (Oxalyl chloride is a toxic liquid and generates carbon monoxide, a toxic gas.) Similarly, they have been condensed in tetrahydrofuran solvent with the aid of a stoichiometric 3-methyl benzothiazole-2-selone/diethyl azodicarboxylate/N,N-dimethylaniline reagent (Mitsunobu et al., Chem. Lett. 1984, 855-858), and they have also have been condensed with the aid of a stoichiometric triphenylphosphine/S-benzyl-S-phenyl-N-p-tosylsulfilimine reagent (Aida et al., Chem. Lett. 1975, 29-32). (The selenium and phosphorous by-products create a toxic waste problem.) They have also been condensed in toluene with catalytic toluenesulfonic acid, prepared in situ from toluene and sulfuric acid (Zardecki et al., Polish Patent, PL 55230, issued 1968 May 15). 2-Phenylethyl benzoate has also been prepared from 2-phenylethyl alcohol and benzoic anhydride in dichloromethane solvent with vanadium salts as catalysts (Chen, U.S. Pat. No. 6,541,659, issued 2003 Apr. 1) or with bismuth tris(trifluoromethanesulfonate) catalyst (Orita et al., Angew. Chem. Int. Ed. 2000, vol. 39, 2877-2879). It has also been prepared from 2-phenylethyl alcohol and benzoic anhydride in N,N-dimethylformamide solvent with equimolar 1,1,3,3-tetramethylguanidine (Kim et al., Bull. Korean Chem. Soc. 1984, vol. 5, 205-206).